AT91F40416 ATMEL Corporation, AT91F40416 Datasheet - Page 3

• Manufacturer Part Number: AT91F40416
• Description: At91 Arm(r) Thumb(r) Microcontroller
• Manufacturer: ATMEL Corporation

Functional
Description
RTC Chip Select
(cs)
1302B–07/01
The RTC provides a full Binary-Coded Decimal (BCD) clock which includes century (19/20),
year (with leap years), month, date, day, hours, minutes and seconds.
The valid year range is 1900 to 2099, a two-hundred year Gregorian calendar achieving full
Y2K compliance.
The RTC operates in 24-hour mode.
Corrections for leap years are included (all years divisible by 4 being leap years, including
year 2000). This is correct up to the year 2099.
The RTC has the ability to be remapped inside the AVR I/O address range. A small amount of
glue logic must be inserted to generate the cs signal. To access the internal I/O locations of
the RTC, the following condition must be true:
Under this condition, iore, iowe and adr are used to access the internal RTC I/O for reading or
writing. The cs input is generated from the decoding of the five AVR adr MSBs. To obtain the
Base Address (BaseAdr) for RTC addressing, use the following logic:
Where the value of cs_adr is assigned by the designer; the binary value {cs_adr[4:0], 0} is the
Base Address (BaseAdr) for RTC addressing.
The BaseAdr and corresponding restrictions for each value of cs_adr are shown in Table 2.
Table 2. cs_adr/BaseAdr
The 1-bit adr provides the offset which locates the RTC registers, as shown in Table 3..
Table 3. RTC Address/Data Registers
adr
0
1
cs = 1
cs = (adr[5:1] = = cs_adr[4:0])
cs_adr
0x00
0x01
0x0F
0x10
0x1b
0x1c
0x1F
.
.
.
.
.
.
.
.
.
.
RTC Register
RTC Internal Address Register
RTC Internal Data Register
BaseAdr
0x1E
0x3E
0x00
0x02
0x20
0x36
0x38
.
.
.
.
.
.
.
.
.
.
Not Allowed
Not Allowed
Comment
Allowed
–
–
–
–
.
.
.
.
.
.
.
.
.
.
RTC
3